Micro-determination of arsenic in aqueous samples by image scanning and computational quantification

Abstract

Arsenic is highly toxic in all of its forms found in natural groundwater. An improved method for the estimation of inorganic arsenic at low levels (μg L⁻¹) in water has been proposed. The method involves the generation of arsine in a specially designed cell by borohydride reduction of arsenite (AsO₂¹⁻). The resulting arsine is passed through a filter paper pre-dipped in mercuric bromide solution giving a yellowish brown complex. The color intensity of the spots is calculated by scanning the spotted paper and analyzing the image using specially designed software. The method was found to be effective at trace levels having a linear response at the concentration range 2–20μg L⁻¹ (8–80ng). The detection limit of the proposed method is 1 μg L⁻¹ (4 ng) which can be reduced further by making some modifications to the apparatus. The method was successfully applied to the analysis of synthetic samples and field samples of water.